Struct heron::rapier_plugin::rapier2d::crossbeam::utils::CachePadded [−]
#[repr(align(128))]pub struct CachePadded<T> { /* fields omitted */ }
Expand description
Pads and aligns a value to the length of a cache line.
In concurrent programming, sometimes it is desirable to make sure commonly accessed pieces of
data are not placed into the same cache line. Updating an atomic value invalidates the whole
cache line it belongs to, which makes the next access to the same cache line slower for other
CPU cores. Use CachePadded
to ensure updating one piece of data doesn’t invalidate other
cached data.
Size and alignment
Cache lines are assumed to be N bytes long, depending on the architecture:
- On x86-64, aarch64, and powerpc64, N = 128.
- On arm, mips, mips64, and riscv64, N = 32.
- On s390x, N = 256.
- On all others, N = 64.
Note that N is just a reasonable guess and is not guaranteed to match the actual cache line length of the machine the program is running on. On modern Intel architectures, spatial prefetcher is pulling pairs of 64-byte cache lines at a time, so we pessimistically assume that cache lines are 128 bytes long.
The size of CachePadded<T>
is the smallest multiple of N bytes large enough to accommodate
a value of type T
.
The alignment of CachePadded<T>
is the maximum of N bytes and the alignment of T
.
Examples
Alignment and padding:
use crossbeam_utils::CachePadded;
let array = [CachePadded::new(1i8), CachePadded::new(2i8)];
let addr1 = &*array[0] as *const i8 as usize;
let addr2 = &*array[1] as *const i8 as usize;
assert!(addr2 - addr1 >= 64);
assert_eq!(addr1 % 64, 0);
assert_eq!(addr2 % 64, 0);
When building a concurrent queue with a head and a tail index, it is wise to place them in different cache lines so that concurrent threads pushing and popping elements don’t invalidate each other’s cache lines:
use crossbeam_utils::CachePadded;
use std::sync::atomic::AtomicUsize;
struct Queue<T> {
head: CachePadded<AtomicUsize>,
tail: CachePadded<AtomicUsize>,
buffer: *mut T,
}
Implementations
impl<T> CachePadded<T>
impl<T> CachePadded<T>
pub const fn new(t: T) -> CachePadded<T>
pub const fn new(t: T) -> CachePadded<T>
Pads and aligns a value to the length of a cache line.
Examples
use crossbeam_utils::CachePadded;
let padded_value = CachePadded::new(1);
pub fn into_inner(self) -> T
pub fn into_inner(self) -> T
Returns the inner value.
Examples
use crossbeam_utils::CachePadded;
let padded_value = CachePadded::new(7);
let value = padded_value.into_inner();
assert_eq!(value, 7);
Trait Implementations
impl<T> Clone for CachePadded<T> where
T: Clone,
impl<T> Clone for CachePadded<T> where
T: Clone,
pub fn clone(&self) -> CachePadded<T>
pub fn clone(&self) -> CachePadded<T>
Returns a copy of the value. Read more
Performs copy-assignment from source
. Read more
impl<T> Debug for CachePadded<T> where
T: Debug,
impl<T> Debug for CachePadded<T> where
T: Debug,
impl<T> Default for CachePadded<T> where
T: Default,
impl<T> Default for CachePadded<T> where
T: Default,
pub fn default() -> CachePadded<T>
pub fn default() -> CachePadded<T>
Returns the “default value” for a type. Read more
impl<T> Deref for CachePadded<T>
impl<T> Deref for CachePadded<T>
impl<T> DerefMut for CachePadded<T>
impl<T> DerefMut for CachePadded<T>
impl<T> From<T> for CachePadded<T>
impl<T> From<T> for CachePadded<T>
pub fn from(t: T) -> CachePadded<T>
pub fn from(t: T) -> CachePadded<T>
Performs the conversion.
impl<T> Hash for CachePadded<T> where
T: Hash,
impl<T> Hash for CachePadded<T> where
T: Hash,
impl<T> PartialEq<CachePadded<T>> for CachePadded<T> where
T: PartialEq<T>,
impl<T> PartialEq<CachePadded<T>> for CachePadded<T> where
T: PartialEq<T>,
pub fn eq(&self, other: &CachePadded<T>) -> bool
pub fn eq(&self, other: &CachePadded<T>) -> bool
This method tests for self
and other
values to be equal, and is used
by ==
. Read more
pub fn ne(&self, other: &CachePadded<T>) -> bool
pub fn ne(&self, other: &CachePadded<T>) -> bool
This method tests for !=
.
impl<T> Copy for CachePadded<T> where
T: Copy,
impl<T> Eq for CachePadded<T> where
T: Eq,
impl<T> Send for CachePadded<T> where
T: Send,
impl<T> StructuralEq for CachePadded<T>
impl<T> StructuralPartialEq for CachePadded<T>
impl<T> Sync for CachePadded<T> where
T: Sync,
Auto Trait Implementations
impl<T> RefUnwindSafe for CachePadded<T> where
T: RefUnwindSafe,
impl<T> Unpin for CachePadded<T> where
T: Unpin,
impl<T> UnwindSafe for CachePadded<T> where
T: UnwindSafe,
Blanket Implementations
Mutably borrows from an owned value. Read more
impl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
pub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
pub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
pub fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
pub fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
impl<T> DynHash for T where
T: DynEq + Hash,
impl<T> DynHash for T where
T: DynEq + Hash,
impl<T> FromWorld for T where
T: Default,
impl<T> FromWorld for T where
T: Default,
pub fn from_world(_world: &mut World) -> T
pub fn from_world(_world: &mut World) -> T
Creates Self
using data from the given [World]
impl<T> Pointable for T
impl<T> Pointable for T
impl<SS, SP> SupersetOf<SS> for SP where
SS: SubsetOf<SP>,
impl<SS, SP> SupersetOf<SS> for SP where
SS: SubsetOf<SP>,
The inverse inclusion map: attempts to construct self
from the equivalent element of its
superset. Read more
pub fn is_in_subset(&self) -> bool
pub fn is_in_subset(&self) -> bool
Checks if self
is actually part of its subset T
(and can be converted to it).
pub fn to_subset_unchecked(&self) -> SS
pub fn to_subset_unchecked(&self) -> SS
Use with care! Same as self.to_subset
but without any property checks. Always succeeds.
pub fn from_subset(element: &SS) -> SP
pub fn from_subset(element: &SS) -> SP
The inclusion map: converts self
to the equivalent element of its superset.
pub fn clone_type_data(&self) -> Box<dyn TypeData + 'static, Global>
pub fn vzip(self) -> V
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more